U.S. Pat. No. 9,175,670 B2 issued on Nov. 3, 2015, to Lockwood, et al. (hereinafter the '670 patent) describes a post-tensioned concrete tower formed by stacking precast concrete annular segments on a foundation, wherein the diameter of the segments varies in stages over the height of the tower, with a group of segments having one diameter being separated from a group of segments having a different diameter by a transition segment. This tower geometry simplifies the formwork used to precast the segments when compared to tower designs wherein each segment is different as the tower varies gradually in diameter over the height of the tower.